RESEARCH ARTICLE: Evidence on Why Bike-Friendly Cities Are Safer for All Road Users

Biking is increasingly being recognized as a highly sustainable form of transportation. Consequently, a growing number of American cities have seen tremendous growth in bicycle travel, in part because many cities are also investing resources into improving bicycling infrastructure. Aside from the environmental advantages, there is now growing evidence to suggest that cities with higher bicycling rates also have better road safety records. This study attempts to better understand this phenomenon of lower fatality rates in bike-oriented cities by examining 11 years of road safety data (1997–2007) from 24 California cities. The analysis included accounting for crashes across all severity levels, as well as for three classes of road users: vehicle occupants, pedestrians, and bicyclists. Additionally, we looked at issues of street and street network design to help determine the role that these features might play in affecting both bicycling rates and road safety outcomes. Overall, cities with a high bicycling rate among the population generally show a much lower risk of fatal crashes for all road users when compared to the other cities in our database. The fact that this pattern of low fatality risk is consistent for all classes of road users strongly suggests that the crashes in cities with a high bicycling rate are occurring at lower speeds. This agrees with the finding that street network density was one of the most notable differences found between the safer and less safe cities. Our data suggest that improving the streets and street networks to better accommodate bicycles may lead to a self-reinforcing cycle that can help enhance overall safety for all road users.